Conventional 1300 nm lasers are based on the InGaAsP or InGaAlAs quantum-well (QW) active material system on an InP substrate. Unfortunately, these 1300 nm InP-based diode lasers suffer poor lasing performance at high-temperature operation. (See, Belenky et al, IEEE J. Quantum Electron, vol. 35, pp. 1515, 1999.) The InGaAsN material system has also been introduced as a material system with enormous potential for realizing light emitters on GaAs in the wavelength regime of interest for optical communications, namely 1300-1550. (See, M. Kondow et al., IEEE J. Sel. Top. Quantum Electron, vol. 3, pp. 719, 1997.) The poor temperature characteristics InGaAsN QW lasers, (see, for example, Kondow et al., IEEE J. Sel. Top. Quantum Electron. vol. 3, pp. 719, 1997; Harris Jr., IEEE J. Sel. Top. Quantum Electron. vol. 6, pp. 1145, 2000; and Sato, Jpn. J. Appl. Phys. Part 1 vol. 39, pp. 3403, 2000) as well as other types of 1300 nm active regions on GaAs, as alternatives to realize high-performance QW lasers for high-temperature operation.
Unfortunately, early InGaAsN QW lasers suffer from poor lasing performance due to the utilization of nearly lattice-matched InGaAsN. (See, Kondow et al., IEEE J. Sel. Top. Quantum Electron. vol. 3, pp. 719, 1997 and Harris Jr., IEEE J. Sel. Top. Quantum Electron. vol. 6, pp. 1145, 2000.) The nearly lattice-matched or lattice-matched InGaAsN QW lasers require a relatively large N content of approximately 3% with an In content of 9%-12% to adjust the lattice constant back to that of an unstrained material system. The utilization of a high In-content InGaAsN QW active region has been proposed. (See, Sato, Jpn. J. Appl. Phys., Part 1 vol. 39, pp. 3403, 2000.) The concept proposed was to utilize as high an In content as possible in the InGaAsN QW, such that a minimum amount of N content is required to push the peak emission wavelength to 1300 nm. By utilizing this approach, 1300 nm InGaAsN QW lasers with reasonable threshold current densities, on the order of 0.92-1.0 kA/cm2 for devices with a cavity length of approximately 1000 μm have been achieved. Recently, various groups utilizing an In content as high as 30%-40% have been able to realize high-performance InGaAsN QW lasers in the wavelength regime of 1280-1310 nm. (See, for example, Sato, Jpn. J. Appl. Phys., Part 1 vol. 39, pp. 3404, 2000; Livshits et al., Electron. Lett. vol. 36, pp. 1381, 2000; and Tansu et al., IEEE Photonics Technol. Lett. vol. 14, pp. 444, 2000.)
InGaAsN QW lasers with an In content of 40% and N content of only 0.5% have been realized with threshold current densities of only 210 A/cm2 at an emission wavelength of 1295 nm. (See, Tansu et al., Appl. Phys. Lett. vol. 81, pp. 2523, 2002.) From studies on InGaAsN QW lasers with an In content of 35%-43%, a trend toward a reduction in the threshold current densities for 1300 nm InGaAsN QW lasers with increasing In content has been observed. Therefore, it is extremely important to realize high-performance InGaAs QW lasers with a very long emission wavelength, such that it requires a minimal amount of N in the QW to push the emission wavelength to 1300 nm.
InGaAs QW lasers with an emission wavelength beyond 1230 nm, utilizing GaAsP tensile-strained buffer and barrier layers have also been realized with threshold current densities of only 90 A/cm2. (See, Tansu, et al., Appl. Phys. Lett. vol. 82, pp. 4038 2003.) In these lasers, a tensile-strained GaAsP buffer layer acts to partially strain compensate for the QW growth template leading to an improved optical quality for the highly strained InGaAs(N) QW.
Unfortunately, the use of nitrogen in the quantum wells of the InGaAsN QW lasers decreases the quality of the semiconductor crystal, increasing the risk of device failure.